In recent years, metamaterials attract attention in the art. The metamaterial is an artificial material capable of realizing physical properties that may not be found in nature by combining significantly small elements (structures) relative to the wavelengths of electromagnetic waves. By using the metamaterial, it is possible to obtain a material (left-handed material) having both negative electric permittivity and negative magnetic permeability and also having a negative refractive index. In the left-handed material, an energy propagation direction and a wave propagation direction are reversed, and as a result, the Doppler effect or the Cerenkov effect also reversely occurs. Meanwhile, since the refractive index can be negative, a perfect lens capable of exceeding a refraction limitation or a super lens capable of obtaining a sub-wavelength resolution by enhancing a near-field has been proposed. In addition, cloaking, MRI electromagnetic wires, perfect absorbers, and the like have been proposed using such a metamaterial characteristic.
The characteristic of the metamaterial is noticeably influenced by a material and a structure. In particularly, it is necessary to sufficiently reduce a size of the structure relative to a wavelength of the electromagnetic wave. For this reason, techniques of manufacturing the metamaterial using a nanofabrication technique such as FIB (focused ion beam) fabrication have been proposed (refer to Non-patent Literature 1). Furthermore, a metamaterial based on a fishnet structure made of Ag and magnesium fluoride has been proposed (refer to Non-patent Literature 2).